Study design and patients
This retrospective study was approved by the Ethics Committee of the Second Affiliated Hospital of Xuzhou Medical University. The need for individual consent was waived by the committee.
The inclusion criteria were: 1) underwent total hip arthroplasty in 2015 or 2019; 2) received general anesthesia before surgery; 3) 65–90 years of age; and 4) American Society of Anesthesiologists (ASA) gradesⅠ-Ⅲ. The exclusion criteria were: 1) serious chronic diseases of the heart, lung, or brain; 2) history of chronic pain and chronic use of opioids; 3) history of related drug allergies; 4) intellectual or understanding disorders, unable to communicate normally; or 5) failure to complete the operation and was discharged from the hospital.
All included patients were divided into two groups based on whether preoperative suprainguinal fascia iliaca block was performed. No-block group: no suprainguinal fascia iliaca block was performed before the operation in 2015. Block group: suprainguinal fascia iliaca block was performed before the operation in 2019.
All patients underwent ECG, peripheral oxygen oxygenation (SPO2), invasive radial arterial pressure, end-tidal CO2, and bispectral index (BIS) monitoring during the operation and underwent all surgical procedures under general anesthesia. The patients in the block group received suprainguinal fascia iliaca block 15 min before general anesthesia by the same anesthesiologist who was specifically trained in ultrasound-guided nerve block.
Suprainguinal fascia iliaca block was performed according to the method described by Bullock et al. , but was conducted under the guidance of an in-plane. The patient was placed in the supine position, and the position of the anterior superior iliac spine was marked. Routine gloving, disinfection, and draping were conducted. A high-frequency linear array probe (6–13 Hz, Sonosite) was applied to sterile ultrasound gel. The probe was transversely placed over the anterior superior iliac spine (Fig. 1). The hypoechoic image of the anterior superior iliac spine was shown on screen. The ultrasound probe was rotated towards the umbilicus until it clearly showed the anterior superior iliac spine, iliacus, fascia iliaca, medial internal oblique, transversus abdominis, and psoas major muscle. The suprainguinal fascia iliaca gap lies between the fascia iliaca and iliacus. Under ultrasound, using the in-plane technique, a 10-cm puncture needle was inserted from the umbilicus to the anterior superior iliac spine. When the tip of the needle reached the space between the fascia iliaca and iliacus (Fig. 2), 2 ml of normal saline was injected to expand the gap between the fascia iliaca and iliacus. Then, 20 ml of 0.375% ropivacaine was injected. The diffusion of the liquid up and down along the fascia iliaca and iliacus was monitored by ultrasound.
In the two groups, general anesthesia was induced with fentanyl 50 µg, propofol 1-1.5 mg/kg, rocuronium 0.6 mg/kg intravenously (i.v.), and 5 ml of 2% lidocaine on the supraglottic and subglottic surface before tracheal intubation. General anesthesia was maintained with sevoflurane 1.0-1.5%, and remifentanil 0-0.3 µg/kg/min (according to the BIS and hemodynamics) and continued until skin closure. The patients were ventilated with 50/50 oxygen/air mixture through tracheal intubation to maintain an end-tide CO2 between 35 and 45 mmHg. Before surgically suturing the skin, ondansetron 8 mg, ketochromic acid 30 mg, and fentanyl 15 µg were administered intravenously. During the operation, the vital signs were maintained at 80%-120% of baseline for systolic blood pressure (SBP) and 55–75 bpm for heart rate (HR). If necessary, vasoactive drugs such as phenylephrine, esmolol, urapidil, etc., were used to maintain the values.
After the operation, the patients were sent to the post anesthesia care unit (PACU), where they were monitored for at least 30 min. When the patients opened their eyes spontaneously, responded to verbal commands, and respiratory efforts were within the normal clinical range, the tracheal tube was removed. A bolus of 10 µg of fentanyl was intravenously given at 10-min intervals until the visual analog score (VAS) was < 4. The level of sedation was recorded as Ramsay scores. If the patients experienced severe sedation or had a Ramsay sedation score of > 5 or respiratory depression, then the fentanyl administration was discontinued. When the patients were fully awake and had stable VAS of ≤ 4, they could be transferred to the general ward. All patients were provided with a patient-controlled intravenous analgesia (PCIA) pump with a 10-µg fentanyl bolus and a 20-min lockout period with no background.
The baseline data of the patients enrolled, such as age, sex, body mass index, ASA grades, and adverse events after surgery were collected. Besides, the intraoperative remifentanil dosage, time to tracheal extubation, time spent in PACU, fentanyl dosage given by intravenous titration in PACU and given by PCIA within 48 h after surgery, VAS score (with 0 indicating no pain and 10, the worst imaginable pain) at rest and during movement on the first and second days after surgery, any complications and adverse events within 48 h after surgery were recorded.
Statistical analysis was performed using SPSS 17.0 (SPSS Inc., Chicago, USA). The Kolmogorov-Smirnov test was used to determine the normal distribution of continuous data. Normally distributed data were presented as means ± standard deviations and analyzed using Student’s t-test. Continuous data with a skewed distribution were presented as medians (interquartile range) and analyzed using the Mann-Whitney U-test. Categorical data were presented as numbers and percentages and were compared using the chi-square test or Fischer’s exact test. Two-sided (except for the chi-square test) P-values < 0.05 were considered statistically significant.